Feizhou wrote:
I will have a look at using Procmail or Postfix as you and Feizhou have mentioned as we're rebuilding a couple of these servers currently.
procmail is a resource hog. If you do not have to use it, do not. If you need some filtering, maildrop may be a better choice.
Sendmail + MimeDefang is probably the most efficient combination but spamassassin is the real resource hog wherever it runs.